Re: [PATCH] SPI: turn transfers from arrays to linked lists

[David Brownell <david-b@pacbell.net>]

On Friday 23 December 2005 6:06 am, Vitaly Wool wrote:
> Hi,
> 
> the patch inlined is changing the SPI core and its users to have
> transfers in the SPI message structure as linked list not as an array,

It basically looks OK.  I've updated it a bit, and will include an
updated version in any future updates of mine.  (Right now I have
to merge your second version with my updated one ... )

So we'll be well on the way to agreeing on a single SPI framework
to evolve and integrate against.  


> -	req->msg.transfers = req->xfer;
> -	req->msg.n_transfer = 6;
> +	for (i = 0; i < 6; i++)
> +		list_add_tail(&req->xfer[i].link, &req->msg.transfers);

More expensive, but not in a way that will often matter much.  That
one's part of one-time init, for example.  And the attached code
uses the spi_message_add_tail(transfer, message) you had mentioned.


> +	DECLARE_SPI_MESSAGE(m);

The updated code has only an spi_message_init() function.


>  
> -		for (;;t++) {
> +		list_for_each_entry (t, &m->transfers, link) {...}

...

> -		tmp = m->n_transfer - 1;
> -		tmp = m->transfers[tmp].cs_change;
> +		if (t)
> +			tmp = t->cs_change;

Bug:  "t" is non-null but invalid there.  (Fixed.)